The collection is arranged into series by correspondent. Series IV contains two small silhouette drawings not directly related to the correspondence.
- Series I. Correspondence between Hugh Henry Brackenridge and Alexander Addison, 1796-1798
- Series II. Correspondence between William Findley and Alexander Addison, 1791-1794
- Series III. Correspondence between Charles Nisbet and Alexander Addison, 1786-1803
- Series IV. Miscellaneous